Climate change might increase the invasion potential of the alien C4 grass Setaria parviflora (Poaceae) in the Mediterranean Basin

Aim  Current climate change is supposed to be beneficial to many biological invaders, especially to C4 alien plants. While several experiments have been dedicated to measuring alien plants’ response to increased atmospheric CO2 concentration, very few studies have been undertaken to measure the response of alien plants to warming. This study was aimed to test experimentally whether the predicted climate change in the Mediterranean Basin could be beneficial to the alien C4 grass Setaria parviflora (Poir.) Kerguelen. Location  Three populations of S. parviflora from Corsica, southern France, were grown in Montpellier, southern France. Methods  The C4 alien grass S. parviflora was exposed to artificial climate change conditions for 3 years in open field and in competition with the local native community. We measured the response to artificial warming of +1.5 and +3 °C and artificial drought (−30% precipitation) versus ambient conditions for phenology, biomass and fecundity of S. parviflora. We compared the response of S. parviflora individuals to the response of the local community. Results  Artificial warming strongly enhanced the biomass and the fecundity of S. parviflora, while it decreased or did not affect the biomass and fecundity of the local community. The phenology (onset of growth, first spike pollinating and fruit ripeness) of S. parviflora was advanced significantly and explained the changes observed in biomass and fecundity. Main conclusions  Here, we report a positive effect of climate change on the growth and fertility of S. parviflora, a C4 alien plant. Our results suggest that climate change predicted for the next decades in the Mediterranean Basin might substantially enhance the performance of S. parviflora, potentially increasing its invasion success.